This is a comprehensive study of lung inflammatory mechanisms which lead to intraalveolar and interstitial reactions. Reactions are produced by immunological approaches (immune complexes; antibody to Type II cells, to angiotensin converting enzyme and to lung basement membrane). The outcome of these reactions is being assessed as well as the relevant mediators. The effects of complement and lymphokine mediators in cultured lung cells are being probed. The role of prostaglandins in facilitating or interfering with lung inflammatory reactions is being assessed. Regulation of enzyme secretions from alveolar macrophages is being determined. What controls proliferative and endocytic responses of macrophages is under study. All of these approaches are aimed toward a comprehensive undertaking of lung inflammatory reactions.